In 1986, the Food and Drug Administration issued regulations approving irradiation of foods as a treatment that would not put public health at undue risk of harm. Because irradiation resulted in the presence of chemicals in foods that do not exist otherwise, the FDA dealt with irradiation, for rule-making purposes, in the same fashion as it would deal with a proposed food additive.
Scientific studies addressing the health effects of those chemicals — called unique radiolytic products, or URPs — are not extensive. Because the radiolytic products make up only a minuscule percentage of the food treated, they are difficult to isolate and their toxicity is difficult to assess through the customary process of giving exaggerated doses of them to laboratory animals. In issuing its regulations on irradiation, the FDA wrote: “The current state-of-the-art toxicity tests are not sensitive enough to detect the potential toxicity of URPs at these low levels unless the URPs are far more potent than experience in the radiation chemistry of foods and in toxicology would suggest.”1
Several reputable scientists have disputed the FDA’s presumption of the URPs’ innocence. Many of the identified URPs are known to be mutagenic — that is, they interact with cells in the body in a fashion that causes the cells to mutate. Mutagenic agents are almost always carcinogenic — cancer-causing — as well. The FDA does not deny this: it says, rather, “the chemical differences between foods irradiated at the doses allowed by this regulation and nonirradiated foods are too small to cause concern about the safety of the irradiated foods.”
Evidence exists, however, that the FDA may be underestimating the effects of irradiation on food. When freshly irradiated wheat was fed to five malnourished children in India in the 1970s, four of them exhibited an abnormal cell condition known as polyploidy within four weeks of the start of treatment. By contrast, a control group of 10 malnourished children, fed the same diet but without the freshly irradiated wheat, showed not a single polyploid cell. A follow-up study of two children fed the irradiated wheat showed that all abnormal cells disappeared within 24 weeks after the feeding stopped.2
The Indian study is unusual in that it employed human subjects, something not customarily done because of ethical concerns. It is just one among many studies of irradiation, however, that suggest the process alters food in ways that could harm human health. A survey of the literature conducted by Richard Piccioni, Ph.D., found “dozens of such studies…, observed in a variety of biological systems, published by a variety of authors in a variety of peer-reviewed scientific journals over a period of twenty years. Proponents of food irradiation commonly claim that the chemical changes occurring in irradiated foods are thoroughly understood, and that there have been no studies indicating the formation of known mutagens or carcinogens. In fact, a substantial number of studies can be found in the open scientific literature indicating the presence of known mutagens, carcinogens, or cytotoxic [cell-killing] substances in food or food components which have been irradiated… In short, the available scientific literature provides evidence to make a strong presumption of carcinogenicity in some if not all irradiated foods. The question is one of quantifying the risk.”3
Salmonella Threat
As a general rule of thumb, the less complex the organism, the higher the dose of radiation required to kill it.4 Thus, irradiation of pork and poultry products, where the target organisms are Trichinella and Salmonella respectively, involves doses 100 times greater than that for most fruit.
As Piccioni notes, “all of the concerns of the presence of trace mutagens or carcinogens in foods irradiated at ‘low’ doses of 100,000 rads are only greater at doses of one million rads, required for even partial Salmonella inactivation.”
Over and above those concerns is the prospect that the irradiation process could leave some Salmonella cells alive and mutated in a way that makes them more virulent. In recent years, the use of what are called “sub-therapeutic” doses of antibiotics in cattle and poultry feed, for example, has led to the evolution of antibiotic-resistant strains of the bacteria. When humans become infected with these new and improved versions, treatment by antibiotics is ineffective, resulting in increasing severity of symptoms.
As Piccioni notes, “Major unresolved microbiological questions arise regarding the safety of gamma processing of salmonella-contaminated poultry: much of the virulence of recent cases of salmonellosis has been attributed to the presence of antibiotic-resistant strains of the pathogen, due in turn to the use of these antibiotics in the poultry industry. The addition of a highly mutagenic processing procedure, namely gamma irradiation, on poultry carcasses still containing low levels of antibiotics is an appalling scenario for the appearance in the irradiated food of new, antibiotic-resistant strains. This issue has received serious, but not adequate, attention in the scientific literature.”
In any event, industry support for the irradiation of beef and poultry products is lukewarm. In the July 1993 issue of Meat & Poultry: The Business Journal of the Meat and Poultry Industry, an editorial points out the down side of irradiation’s promise: “If processors know their products are ultimately going to be treated by irradiation and thus absolved of pathogens, human nature may simply cause everyone to relax their standards a bit. We can’t risk that.”
An alternative — and far more economical — means of treating poultry for salmonella contamination has been developed recently, involving bathing the carcasses in water and trisodium phosphate, a chemical already in wide use by food processors.
1. Federal Register, April 18, 1986, p.13378.
2. C. Bhaskaram and G. Sadasivan, “Effects of Feeding Irradiated Wheat to Malnourished Children,” American Journal of Clinical Nutrition, Vol. 28 (February 1975), pp.130-135.
3. Richard Piccioni, “Analyses of Data on the Impact of Food Processing by Ionizing Radiation on Health and the Environment,” International Journal of Biosocial Research, Vol. 9 (1987), pp.203-212.
4. See, for example, the editorial in the University of California at Berkeley Wellness Letter of May 1992.
— Patricia Tummons
Volume 6, Number 1 July 1995
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